History of Intelligence Testing

History of Intelligence Testing in Psychology

In psychology, intelligence testing can play an important role in several disciplines such as cognitive psychology and education.

The history of intelligence testing in psychology originates as far as over 2000 years ago. In his work entitled The Republic, Greek philosopher Plato states that:

Especially in Western cultures, we highly value the individual and often ask how and why we are different. As a result, intelligence testing has easily found its place in Western society. Today, these tests have been used to place students in the appropriate class and soldiers in the appropriate assignment.

Types of Intelligence Testing

There are two primary types of intelligence testing: achievement tests and aptitude tests. Let's explore what each of these entails.

In the history of intelligence testing, psychologists are usually focused on designing aptitude tests more than achievement tests.

First Intelligence Test

So where did it all begin? The very first intelligence test attempt was by an English scientist named Francis Galton (1822-1911).

So, it should come as no surprise that Galton was inspired by Darwin's theory of natural selection.

Galton wanted to take this one step further and apply it to intelligence. What if there were a way to measure a person's natural intellectual ability and then encourage people with higher abilities to mate? This radical idea laid the groundwork for an ideology called eugenics which we will discuss later as a major criticism of intelligence testing. But, it also led to Galton attempting something that resembled an intelligence test for the first time.

Fig. 1, The "father of intelligence testing" Francis Galton, commons.wikimedia.org

In 1884, Galton took his first attempt at an intelligence test when assessed the intellectual strengths of 10,000 visitors to the London Health Exhibition. These strengths were based on several factors including sensory sensitivity, reaction time, body proportions, and muscular strength. Unfortunately, the attempt was a bit of a flop, as there was no correlation for either adults or students. However, the assessment wasn't a total loss as it gave us several useful statistical techniques.

The Father of Intelligence Tests

Officially, the first intelligence test was actually designed by the "Father of Intelligence Tests," Alfred Binet (1857-1911). Believe it or not, going to school was not always required of children. But when a new law was passed in France requiring every child to attend school, they were in desperate need of a way to test their intellectual ability. Many teachers were unfairly basing ability on a child's social background or would wrongly assume that a child is a slow learner if they were less educated.

Binet along with his student, Théodore Simon, were tasked with designing intelligence testing that would help teachers place students in classes that were appropriate for their aptitude. To do this, they figured they would design their intelligence test to measure a child's mental age.

The test is based on the logic that a child who is "bright" should test the same as a typical child that is older and a child who is "behind" should test the same as a typical child that is younger.

Binet did not believe that intelligence was simply something we're born with but leaned more towards the belief that environment plays a significant role in a child's aptitude. So his aim was not to design a test that would decide which children were "bright" and which were "behind" but rather design a test that could pinpoint low-scoring children who may need more support in raising their intellectual capacities.

History of Intelligence Testing Timeline

Binet and Simon laid a strong foundation for intelligence testing that followed Binet's death in 1911. The history of intelligence testing timeline includes Lewis Terman's Stanford-Binet Test, William Stern's Intelligence Quotient (IQ), and David Weschler's Adult Intelligence Scale (WAIS).

Lewis Terman Stanford-Binet Test

Binet's intelligence testing would not have made its way to the United States if not for Lewis Terman (1877-1956), a Stanford University professor. While Binet's intelligence testing proved to be useful, it was not perfect.

Terman used Binet's questions and age norms and adapted some of his original items to California kids, added some others, and set new mental age norms. He was even able to expand Binet's original test range to age 12 all the way up to the higher level adults. He named his revised version of Binet's test the Stanford-Binet Test which continues to be used even today.

Fig. 2, Intelligence testing is a tool used by many in the modern day, in different forms, Unsplash.com

William Stern Intelligence Quotient (IQ)

How do we know that Albert Einstein was a genius? Your first thought is probably that he had a high IQ. But what does this actually mean and where does it come from? Originally coined by William Stern, intelligence quotient (IQ) was formed as a measurement for intelligence testing.

IQ is simply a value that some intelligence tests calculate after they've found the test-taker's mental age.

Most people who take an intelligence have an IQ between 85 and 115. Einstein's IQ was estimated between 205 and 225 (so yes, he was pretty smart). Recently, calculating IQ is not as popular especially since it's really only useful for children. It wouldn't make a lot of sense to say a 60-year-old has an IQ of 50 just because they test as well as a 30-year-old. Instead, the term "IQ" in intelligence testing usually references a person's score based on average performance.

Wechsler Adult Intelligence Scale (WAIS)

One of the most widely used intelligence tests was designed by David Wechsler. Unlike the Stanford-Binet intelligence tests, the Wechsler Adult Intelligence Scale (WAIS) gave several separate scores in addition to one overall intelligence score. It tests working memory, verbal comprehension, perceptual reasoning, and processing speed. WAIS is commonly used as part of a psychological assessment for diagnosing and treating mental disorders.

There are 15 subsets in this type of intelligence testing. A few examples include:

• Letter-number sequencing (naming back a series of numbers and letters in alphabetical order or ascending numerical order)

• Vocabulary (naming pictures or defining words)

• Block design (abstract visual processing of an object or structure)

• Similarities (finding commonalities between two objects or ideas)

This intelligence test also has visions for preschool children and school-aged children as well.

Criticisms of Intelligence Testing

The development of intelligence testing has benefited the field of psychology in a major way. However, there are some valid criticisms of intelligence testing that we should discuss.

Binet never wanted his intelligence testing to be a reason to label children and force them into some kind of box that would limit their opportunities. He wanted the tests to help improve education. But in some ways, intelligence testing has been a hindrance for children who have been written off by schools for their low test scores.

Eugenics

A major criticism of intelligence testing is its influence on an ideology called eugenics.

But the issue is, who gets to decide which traits are desirable and which are not? Should we not leave this process to natural selection? We mentioned earlier that the concept of eugenics began with the work of Francis Galton but other psychologists also contributed to this ideology including Henry H. Goddard.

• Goddard was a psychologist who also helped bring Binet's intelligence testing to the United States as well. However, his mission heavily reflected the ideas of the emerging eugenics movement at the time. He advocated for the inhumane practice of sterilizing and segregating the intellectually disabled.

Even Terman supported eugenics as he believed that the results of intelligence testing reflected a person's mental capacity from birth and assumed that some ethnicities were inherently more intelligent than others.

Today, this is a heavily disproved and criticized ideology and has supported racially biased doctrines such as that of the Nazis. This was never Binet's intent of intelligence testing. He simply wanted it to be a way to identify the students who needed more attention to give them the best chance at learning.